P07B4: Transmission Park Position Sensor/Switch A Circuit High

With electronic gear selection the park position sensor/switch reports the park request or position. On GM's shift-by-wire selectors (2017 LaCrosse, XT4/XT5, Bolt EV, later SUVs and pickups) it is the P button, read by two redundant analog sensors A and B with separate 'released' and 'pressed' voltage zones. P07B4 means sensor A reads above its valid zones: GM flags above 853 counts (83.3 % of 5 V), the ICCM above 70 %, after two trips. A short to positive or an open ground is typical. A GM bulletin for the 2017 LaCrosse, XT5 and Bolt EV lists P07B4 when the selector knob is not fully seated or the connector at the shifter is not latched – check that first.

Symptoms

• Check engine light, 'service transmission' or 'unable to shift' message
• Park cannot be selected by button, or the car will not shift out of P
• P button illumination off

Most likely causes

• Signal shorted to positive or ground open
• Selector knob not fully seated or connector not latched
• Sensor in the P button faulty
• Selector or control module

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the fluid level and condition
2. Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
3. Read the input and output speed in live data
4. Check the connector and wiring
5. Check for other related engine codes
6. Consult the manufacturer's procedure for the transmission

Good to know

• Repair difficulty: medium
• It can trigger limp mode.

What each character of P07B4 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 7: Transmission
• B4: Specific fault in that system

Frequently asked questions

Can I keep driving with code P07B4?

Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.

What causes code P07B4?

The most common causes are: signal shorted to positive or ground open; selector knob not fully seated or connector not latched; sensor in the P button faulty.

Related codes

• P07B3Transmission Park Position Sensor/Switch A Circuit Low
• P07B5Transmission Park Position Sensor/Switch A Circuit Performance/Low
• P07B6Transmission Park Position Sensor/Switch A Circuit Performance High
• P07BATransmission Park Position Sensor/Switch B Circuit High
• P07BETransmission Park Position Sensor/Switch A/B Correlation

Sources

• gsi.ext.gm.com: 19OBDG03A Diagnostics
• gsi.ext.gm.com: 19OBDG03B Diagnostics
• static.nhtsa.gov: MC 10116541 9999

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.